In High Intensity Focused Ultrasound (HIFU), a volume of interest is detected during the planning stages and may be marked on medical images, such as magnetic resonance images. For example, an ellipsoid can be quickly drawn over a uterine fibroid. Volumes to be destroyed, so called treatment cells, can be planned in advance and may landmark vessels or other structures to be destroyed. Regions of interest can be drawn to highlight organs at risk and safety margins to organ structures. Once sonications have been carried out, the produced temperature map overlays and thermal doses correspond to signal changes in images where the tissue has been altered with thermal energy. These form the basic HIFU graphical objects. The international application WO2010/113050 discloses delineating anatomical features in images used for image-guided therapy planning. This known delineation makes use of a comparison of the position of anatomical landmarks in the image to reference landmarks.
However, subjects may have external and/or internal motion during a course of sonication. Automatic re-registration algorithms are susceptible to errors when the input image data does not provide sufficient/correct contrast or signal to noise ratio. Landmark-based manual methods need extensive user interaction to define suitable anatomical landmarks and slow down the therapy session. The ISMRM abstract in Proc. ISMRM(2009)443 mentions that a 2D selective navigator is employed to compensate out-of-plane motion.